Lithium ion battery was commercialized from 1990s. Lithium ion batteries are widely used in various kinds of apparatus, such as mobile communications, laptop computers, portable tools, electric bicycles, for the lithium ion batteries having advantages of higher operating voltage, higher energy density, long life cycle, safety performance and memoryless property. According to statistics, the global production of lithium ion batteries were more than 580 million in 2000, the domestic production in China were about 100 million. The global production of lithium ion batteries reached to 1.255 billion in 2003 and 2.71 billion in 2008, and the global production were over 3 billion until 2010. With the development of economy and technology as well as the development of global energy, lithium ion batteries will become the main power source for electric vehicles, which will further promote the development of lithium ion batteries.
In general, after 500-1000 times charging/discharging cycles, the active materials in lithium ion batteries will lose activity, which will cause decrease to battery capacity and the battery will have to be scrapped. The waste battery contains 5%-15% of Co, 2%-7% of Li, 0.5%-2% of Ni, and may further include elements such as Cu, Al, Fe, etc. Ni, Co, Li in waste batteries are first resource having a significant recycling value. The plastic or metal casing, the electrolyte and the electrodes in waste batteries are all valuable resources and have highly recycling values. Furthermore, if the waste batteries are not recycled and thrown away, the soil and water will be polluted due to the waste batteries containing a large amount of metal elements and electrolyte. The organic materials in the electrolyte of waste batteries will also volatilize to cause air pollution and bring serious environmental problems.
Currently, the technology of recycling and regeneration of waste lithium ion batteries has made a great progress. The recycling of waste lithium ion batteries mainly concentrates on the recovery of metals such as cobalt, nickel and lithium, and the resource utilization of waste lithium ion batteries is mainly concentrated on the recycling and reuse of positive electrode materials of the waste lithium ion batteries. The existing methods of recycling waste lithium ion batteries include sintering method, solvent extraction method, dissolution-chemical precipitation method, and biological method.
The sintering method is also known as dry method, in which high temperature is used to process the waste lithium ion battery to get rid of the plastic or metal casing thereof, then flotation process and precipitation process are used to get metal compounds from the waste lithium ion battery. The sintering method is easy to operate but requires high energy consumption, the burning of electrolyte and other ingredients in electrodes can lead to air pollution.
The solvent extraction method is to use the selectivity of organic extraction solvents over different metal ions to achieve separation of metal ions from each other. The solvent extraction method has the advantages of mild operation conditions and good separation effects, but the use of chemical reagent and extracting reagent also causes environmental pollution.
The dissolution-chemical precipitation method is to dissolve the active materials firstly and then add precipitator to precipitate precursor of electrode material, and finally sinter the precursor to get electrode material. This method is relatively simple and easy to operate, but how to select the precipitator and further the precipitation conditions is very important, and the large amount use of chemical reagent also causes secondary pollution to environment.
The biological method is to use microorganism to transfer useful constituents of the waste lithium ion battery to soluble compound which can be dissolved selectively to obtain liquor containing metal. This method has the advantages of low investment, low operation cost, less environmental pollution, etc. However, the negative side of this method is the long processing period, the microbial strain is not easy to culture, the leaching conditions are not easy to control, and the leaching solutions are difficult to be separated.
Chinese patent publication No. CN1585187A discloses a recycling method of positive electrode material in waste lithium ion battery. This method includes cutting the battery casing and taking out the positive electrode, heating the positive electrode to separate the positive material and the current collector, removing conductive agent from the positive material under high-temperature, and sintering the positive material after adding lithium to get positive electrode material. This method is only limited to recycle positive electrode material but not applicable to recycle negative electrode material, and three times heating process during the method leads to high energy consumption.
Therefore, a method, which has preferable effect, simple operation and less environmental pollution, needs to be developed for recycling waste lithium ion batteries, for alleviating the shortage of Cu, Li and Ni resources, solving the problem of environmental pollution by waste batteries, and achieving comprehensive utilization of the resources and protection of the ecological environment.